With the advent of internet in mobile communications networks the networks more and more are used for providing data based services. Streaming video clips to mobile phones or tablets, voice over IP calls and regular internet browsing are now possible on mobile devices. Wireless communications networks based on 3rd-Generation Partnership Project (3GPP) technologies (these include radio-access technologies known as Long Term Evolution (LTE), Long Term Evolution Advanced (LTE Advanced), Universal Mobile Telecommunications System/Wideband Code-Division Multiple Access (UMTS/WCDMA), and Global System for Mobile Communications (GSM)) have limited bandwidth and the ever-increasing number of mobile devices capable of using data services results in dramatic increase of mobile data consumption.
In search for additional bandwidth, wireless network operators turned their attention to WiFi which is widely used in Wireless Local Area Networks (WLAN). The network operators and suppliers of network equipment considered the possibility of using WiFi for purposes extending beyond the role of indoor access to broadband services. Smartphones and other devices (referred to hereinafter as “user equipment,” or “UE”) using 3GPP access networks are today equipped with WiFi interface. Initially this WiFi capability of smartphones was intended for accessing Internet and other data services when the user was indoor where he or she had access to a WiFi network. The decision to switch data connection to WiFi is made in these devices without support from the 3GPP network. The UE detects WiFi network and switches data connection from the 3GPP network to the WiFi network if it is authorised to use said WiFi network. This switch have a character of a handover in the sense that the data connection delivered to a smartphone over 3GPP interface is moved to WiFi interface when the smartphone is in the range of a WiFi network which it is allowed to use. In consequence the data is transmitted over the WiFi interface instead of the 3GPP interface. These WLAN networks in user's homes or offices are not really part of the wireless communications network controlled by the operator. They are private networks that can support individual users rather than wider public.
To address the growing demand for increased network data capacity, operators are leveraging on WiFi coupled with their macro/pico cell deployments to enable capacity offload in a cost effective manner. From the operator's perspective switching from 3GPP access to WiFi access networks brings number of benefits:                WiFi operates on free (i.e. unlicensed) spectrum, which means there is no need for expensive and time consuming work needed to satisfy legal regulations.        WiFi offers huge network capacity boost.        Simplified network procurement processes, this is partly related to WiFi operating on unlicensed spectrum.        Lower Capex investment required compared to other solutions (e.g. so called micro and pico cells).        
The above described 3GPP-WLAN system interworking is a technique defined as a wireless IP connectivity service where the user obtains access via a Wireless LAN technology instead of via 3GPP access network. It shall be possible to deploy the WLAN as an integral part of the 3GPP system or the two systems can be separate. The 3GPP system shall be capable of interworking with one or more WLANs and a WLAN shall be capable of interworking with one or more 3GPP systems. More details on 3GPP system to Wireless Local Area Network (WLAN) interworking can be found in 3GPP TS 22.234 V12.0.0 and 3GPP TS 23.234 V12.0.0.
There is known a solution for supporting handover from a WiMax network to a WLAN network as disclosed in Korean patent application KR1020080056914. In this solution the mobile terminal receives from the WiMax network information about WLAN AP (access point) installation density and if the WLAN AP installation density is below some reference value the WLAN interface is turned off in the mobile terminal. This solution is focused on minimising power consumption by turning off the WLAN interface when it is unlikely that the mobile terminal enters into a range of WLAN AP (the decision to turn off WLAN interface is based on combination of installation density and the speed of the mobile terminal).
There is also known a solution for controlling operation of a WLAN interface in a mobile terminal as disclosed in patent application US2011/0171909A1. In this solution the mobile terminal knows locations of WLAN Access Points, determines its own location and switches on the WLAN interface if it is located in a range (or close to) one of the known WLAN Access Points.
There is also known a technique called multipoint traffic control protocol (MPTCP) where two or more TCP connections run in parallel between User Equipment and the internet. In this way the bandwidth available to the UE is increased by the plurality of connections. Multipath TCP aggregates a set of TCP connections (sub-flows) and distributes load on all interfaces. An example illustration of network stacks of TCP and MPTCP is shown in FIG. 9 and an example of a plurality of TCP flows forming MPTCP connection is shown in FIG. 10.